A period (menstruation) is bleeding from the vagina that happens once a month. A period is part of your menstrual cycle. The menstrual cycle is controlled by hormones. Hormones make the lining of your uterus become thicker. This gets the body ready in case you become pregnant Hormones also cause an egg to be released from an ovary, which is known as ovulation.

Some forms of hormonal contraception (for example the oral contraceptive pill, hormonal IUD, implant or injection) may affect your periods. They may affect how often you get your period and/or the flow.

The pill

Usually, oral contraceptive pills (the pill) will make your periods lighter. You may find that your periods are irregular and your flow changes while your cycle adjusts to the changing hormones.

After taking the pill for around 6 months, your periods should form a regular routine. Some people say that their periods stop while taking the contraceptive pill.

The main type of oral contraceptive pill is the combined oral contraceptive pill. This type of pill has the hormones progestogen and oestrogen (also spelled estrogen). The combined pill might make your periods more regular and improve premenstrual syndrome (PMS).

The combined pill often comes in a packet of 28 pills, with 21 active pills and 7 ‘inactive’ pills. Some packets contain 24 active pills and 4 inactive pills. It is sometimes possible to skip the inactive pills to avoid a withdrawal bleed. Talk to your doctor about whether this is possible. Always take prescription medicines as instructed.

The mini pill

The mini pill contains only a small dose of the hormone progestogen. It is often used in people who are breastfeeding. It can cause irregular periods.

Contraceptive injections

Contraceptive injections can also cause your periods to be irregular for a while before your body adjusts to the hormones. Some people have heavier periods when they start hormonal injections. Over time, people’s periods usually become much lighter and less regular.

Contraceptive implants

A contraceptive implant can give you irregular periods. Things should improve after about 3 months. About 1 in 5 people won’t have periods after this time.

Hormonal intrauterine devices and your periods

A hormonal intrauterine device (IUD) may also affect your periods. IUDs are sometimes called a ‘coil’. Some IUDs release the hormone progestogen (brand names Mirena and Kyleena).

If your IUD has been fitted in the last 6 months, you may have some irregular bleeding or spotting (spotting is bleeding between your periods).

After 6 months, many people find that their periods completely stop. Other people find their periods become much lighter or irregular.

Contraceptive hormonal vaginal ring

There is also a contraceptive vaginal ring available. It contains low doses of oestrogen (estrogen) and progestogen. It can help control your periods and often makes bleeding more regular, lighter and sometimes less painful.

Talk to your doctor about the benefits and risks of hormonal medicines and their effects on periods.